[VPlan] Remove redundant setting of insert point in ::executePlan (NFC).

The entry block is a VPIRBasicBkock wrapping the original loop's
preheader, so the insert point doesn't need to be set.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -7709,11 +7709,9 @@ DenseMap<const SCEV *, Value *> LoopVectorizationPlanner::executePlan(
 
   // 0. Generate SCEV-dependent code in the entry, including TripCount, before
   // making any changes to the CFG.
-  if (!BestVPlan.getEntry()->empty()) {
-    State.CFG.PrevBB = OrigLoop->getLoopPreheader();
-    State.Builder.SetInsertPoint(OrigLoop->getLoopPreheader()->getTerminator());
+  if (!BestVPlan.getEntry()->empty())
     BestVPlan.getEntry()->execute(&State);
-  }
+
   if (!ILV.getTripCount())
     ILV.setTripCount(State.get(BestVPlan.getTripCount(), VPLane(0)));
   else